Field of the Invention
The present invention relates to a battery device, a charging device that charges the battery device, a method, and a storage medium.
Description of the Related Art
A method of determining a degradation state of a battery device includes a method of determining the degradation state of the battery device by using the number of times of battery charging (see Japanese Patent Laid-Open No. 5-172914). Japanese Patent Laid-Open No. 5-172914 discloses a method of determining a life of a battery by using the number of times of battery charging.
A lithium-ion battery easily degrades when the battery is charged from a state wherein a depth of discharge (DOD) is large. However, according to the method described in Japanese Patent. Laid-Open No. 5-172914, a problem occurs that the degradation state of the battery device is determined without taking into account the DOD.
In addition, it is not necessarily the case that the lithium-ion battery hardly degrades when the battery is charged from a state wherein the DOD is small. A progress degree of the degradation state of the battery device may vary depending on a charging voltage when the charging is started. However, according to the method described in Japanese Patent Laid-Open No. 5-172914, a problem also occurs that how the charging voltage at the time of the charging start affects the degradation state of the battery device is not taken into account.
As the method of determining the degradation state of the battery device, a method of determining the degradation state of the battery device from an internal resistance of battery cells is conceivable in addition to the method of determining the degradation state of the battery device by using the number of times of battery charging.
However, according to the method of determining the degradation state from the internal resistance of the battery cells, since it is difficult to accurately calculate the internal resistance, an issue occurs that it is difficult to accurately determine the degradation state of the battery device.
In addition, as the method of determining the degradation state of the battery device, a method of determining the degradation state of the battery device by providing a coulomb counter circuit or the like in the battery device and using the coulomb counter circuit or the like is conceivable in addition to the method of determining the degradation state of the battery device by using the number of times of battery charging.
However, according to the method of determining the degradation state of the battery device by using the coulomb counter circuit or the like, an issue occurs that a circuit scale of the battery device is enlarged to increase costs. Furthermore, an issue also occurs that, since the coulomb counter circuit or the like needs to be regularly operated, power consumption of the battery device is increased, and the remaining power amount of the battery device is decreased at a still faster pace.